By State police do you mean State Troopers, cause every state has those. The one s who have the who have most control are forest Rangers, they can search your car and home without search warrant.
Yes,a state police can investigate a state case.
Maryland State Police was created in 1921.
to be a police officer you need to attend a state approved police academy and be state certified in the state you live in.
I believe that the Texas Rangers were the first "state police".
In a police state, the government would control the actions of police.
It was the Pennsylvania State Police.
Virginia State Police was created in 1932.
Indiana State Police was created in 1933.
Louisiana State Police was created in 1922.
Idaho State Police was created in 1919.
California State Police was created in 1887.
Massachusetts State Police was created in 1865.